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By N.K Agarwal (ex-Director, GSI)
Citation preview
2/8/2015
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Earth Scienceor
GeologyFebruary-2015
n.k.agarwal
ex-Director, GSI
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Geology is the History of Earth
Geology is the Study of Earth
Geology
In its Most Simple Meaning :
How earth was formed ?
How old is earth ?
What is earth made up of ?
Why earth is called a unique planet ?
What are the biotic and a-biotic components of earth ?
What are Natural Resources ?
What is its Environment ?
How to manage Natural Resources ?
Interdisciplinary
Science
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Main Branches of Geology
1.Physical Geology
2.Geomorphology & Environmental Geology
3.Petrology
4.Stratigraphy
5.Paleontology
6.Structural Geology
7.Geochronology
8.Economic Geology Minerals Oil & Gas etc.
9.Seismo-Tectonics
10.Engineering Geology
11.Geochemistry
12.Geophysics etc. 4
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ENERGY and MASS TRANSFORMATION
The Big Bang~15 billion years ago
B
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Ma= Million Anum = 10x6 Ga= Giga Anum = 10x9
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V
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The Origin of the Earth
~15 billion years ago :The Earth and the other 8 planets and the
Sun accreted at about the same time from a
vast cloud of dust and gas (nebula).
~5 billion years ago :The nebula began to gravitationally contract,
began to rotate and flattened. Eventually, the
Sun ignited (fusion) and the newly formed
planets began to differentiate - heavier
elements and chemical components sank to
the center and rocky material formed the
crust. The newly formed planets and moons
released gas forming early atmospheres.
Making of Solar System
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Making of Solar System
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Solar System
Inner Planets Outer PlanetsAsteroids 9
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Earth From Outer Space
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http://ep.yimg.com/ca/I/spaceimages_2114_11521197
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Indian Sub-Continent from Outer Space
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Uttarakhand from Outer Space
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University of Petroleum and Energy Studies
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What's the first
thing that you
notice about
our planet
when you see
this image?
The Earth is composed
of several integrated
parts (spheres) that
interact with one
another:
Atmosphere
Hydrosphere
Solid earth (lithosphere)
Biosphere
Unique Planet - Earth
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Atmosphere:
The swirling clouds of the atmosphere represent the
very thin blanket of air that
covers our planet. It is not
only the air we breathe, but
protects us from harmful
radiation from the sun.
Hydrosphere:
The global ocean is the most prominent feature of
our (blue) planet. The
oceans cover ~71% of our
planet and represent 97% of
all the water on our planet.
Unique Planet - Earth
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The Earth
System
Biosphere:
Includes all life forms on Earth - concentrated on land,
water and air- Plants and
Animals.
Solid Earth:
Represents the majority of the Earth system. Most of
the Earth lies at inaccessible
depths.
Unique Planet - Earth
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Inside the Earth
Crust
Mantle
Liquid
Core
Solid
Core
Crust thickness varies
From 5-70 km
1216 km
3486 km
0
6357 km at Poles
Density (gm/cm3)
Earth 5.517
Continental Crust 2.80
Oceanic Crust 2.90
Mantle 4.53
Outer Core 9.71
Inner Core 16.0 18
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The Earth's interior is
characterized by a gradual
increase in temperature,
pressure and density with
depth.
At only 100 km depth, the
temp is ~1300C.
At the Earth's center, the
temperature is >6700C.
The pressure in the crust
increases ~280 bars for
every kilometer depth.
Earth's Internal Structure
Polar Radius ~6357 km
Equatorial Radius ~6378 km
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Depth wise the Earth consists of 3 major divisions marked by differences in chemical composition Crust, Mantle and Core
Crust: Outermost rigid layer - 2 types:
1. oceanic - 3-15 km thick and is composed
of basalt (igneous).
Young (3.8
billion years old).
Earth's Internal Structure (contd.)
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Mantle: comprises ~82% of the Earth by
volume (~2900 km).
The mantle is
characterized denser
rocks and is able to flow
(plastically) at very slow
rates.
Core: composed of iron, nickel and other
minor elements.
The outer core is liquid
capable of flow and
source of the Earth's
magnetic field (~2270km).
The inner core is solid
Fe-Ni (~1216km).
Earth's Internal Structure (contd.)
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ATMOSPHERE
HYDROSPHERE
BIOSPHERE
SOLID EARTH
EARTH A UNIQUE PLANET
Only Planet known to have Life Supporting
Conditions
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Biotic and A-Biotic Constituents
Rocks and Minerals
Soil
Water
Gases
All Life Forms
Plants
Animals
Terrestrial
Land
Fresh Water
Marine
Most of Solid Biotic
Constituents are
Made up of Minerals
and Rocks
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What is Mineral ?
It is a Natural Inorganic Solid Substance with a
Definite Range of Chemical Composition,
Atomic Structure and Measurable Properties.
What about Coal, Oil, Water
Coral etc. ?
Loose Definition of Mineral !
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How Many Minerals are known ?
> 3500 are Identified
About 100 are Commonly found
About 30 are important
rock forming minerals.
Rock forming minerals
are composed of the most
abundant elements found
in the earths crust
Abundance of elements
in earths crust (% Wt.)
1 Oxygen 46.71
2 Silicon 27.69
3 Aluminum 8.07
4 Iron 5.05
5 Calcium 3.65
6 Sodium 2.75
7 Potassium 2.58
8 Magnesium 2.08
9 Titanium 0.62
10 Hydrogen 0.14
11 Phosphorus 0.13
12 Carbon 0.094
13 Manganese 0.09
14 Sulphur 0.002
15 Barium 0.050
Rest 0.244
Total 100.0
15 elements constitute 99.75 %
of Earths crust25
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Rocks and Minerals Raw MaterialLife Revolves around Rocks & Minerals
Needle
Tooth paste
Talcum Powder
Utensils
Electronics
Appliances
Fertilizers
Agriculture - Soil
Energy Fuels (Coal, Oil & Gas)
Energy Nuclear
Ornaments and Gem Stones
Soil
Forest
Direct Useable
Minerals & Rocks
Indirect Useable
Minerals & Rocks
Gold, Silver
Clay
Sand
Gravel, boulder
Lime
Gem Stones
Glass
Copper, Zinc, Lead, Steel
Borax, Sulphur26
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Important Mineral Compositions
S.No. Composition
1 Oxides
2 Silicates
3 Carbonates
4 Phosphates
5 Sulphides
6 Nitrates
7 Borates
8 Hydrocarbon Compounds
9 Mixed
10 Native
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Common Rock Forming Minerals (simplified)
S.N. Name S.N. Name
1 Quartz* 9 Montmorinillonite*
2 Orthoclase
Microcline
Albite etc.
10 Chromite
Hematite*
Magnetite*
Pyrolusite*
Psilomelane*
3 Muscovite, Biotite, Chlorite 11 Garnet
4 Calcite*
Dolomite*
Magnesite*
12 Epidote
Sillimanite*
Kyanite*
5 Amphiboles 13 Pyrite*
Chalcopyrite*
Pyrrhotite*
6 Pyroxenes 14 Peat, Lignite, Coal,
7 Olivine 15 Apatite*
8 Kaolin* 16 Gold**, Silver** etc.
* - Also forms mineral deposits ; ** - Occurs in small quantities in some rocks.28
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Soils
Alluvium Indo Gangetic Brahmaputra Plains Terraces along valleys
Coastal Plains
Lateritic Laterite, Bauxite, Clays etc. Sand Rock, Silica Sand
Weathering and Erosion of Rocks
Generates Soils Transported
Residual
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Natural Resources
Mineral Resources
Water Resources
Plant & Animal Resources
Rocks & Minerals
Soil
Water Bodies
Ground Water
Forest & Wild Life etc.
Renewable & Non-Renewable Resources
Finite Resources30
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Environment
Total biotic & a-biotic components surrounding us
Mutual relation and interrelation
Sustainability
Man is Unique pest, parasite and predator
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Natural Resource Management
Quality of Life
Resilience
Over Exploitation
Conservation
New Resources & Replacement
Global Climate Change
Environment Protection
Sustainable Development32
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To Understand Use of Geology in Oil &
Gas Exploration
Our Main Concern
All Oil & Gas Exploration and Exploitation
revolves around Geology
To Understand What is Oil & Gas Exploration
or
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Understanding of Geology tells us where to
search for Oil & Gas and How to Exploit it
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What is Applied Geology
?In most simple meaning : It is the
application of the knowledge of Geology
for the benefit of mankind Improving the
Quality of Life
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This chapter helps you in understanding :
1) What is Geology & Applied Geology?
2) How Mineral Resources including Oil & Gas
related to the knowledge of Geology?
3) Relation between Knowledge of Geology and
Sustainable Development
Summary :
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